A biological photometer is an instrument, which permits to measure simply and easily blood circulation, blood circulation dynamics and hemoglobin variation in blood inside a living body with a low restriction to a subject. As such a biological photometer, for example, JP-A-57-115232 and JP-A-63-275323 disclose instruments in which a light having a wavelength in a region of visual to infrared is irradiated into a living body and a light transmitted inside the living body or a light reflected near the surface of the living body are detected to measure the above referred to information inside the living body. With these instruments, through irradiating light from a plurality of points as well as detecting light from a plurality of points near the irradiation points, information inside the living body in the region covered by these points can be obtained. A graph displaying a hemoglobin variation in the covered region in a form of a map is called as topography and a clinical application of the topography is expected and is now being reduced into practice.
As a clinical application of a biological photometer, for example, in a case when a head portion is the measurement object, local focus identification during epileptic seizure and diagnosis of hypo function in melancholia and integration dysfunction syndrome (schizophrenia) due to hemoglobin variation inside the brain are enumerated. More specifically, it is confirmed by making use of a biological photometer that at the beginning of epileptic seizure a steep hemoglobin variation occurs (WATANABE Eiju et al. Tokyo Police Hospital “Clinical Application of Photo Topography” MEDIX Vol. 30). Further, it is reported that in connection with melancholia and schizophrenia an abnormality in a hemoglobin variation pattern at the frontal lobe occurs (FUKUDA Masato et al. “Functional Brain Imaging in Psychiatry Using Multi-Channel Near-Infrared Spectroscopy” Clinical Psychiatry, Vol. 30, No. 8, Gunma University Affiliated Hospital).
However, since a conventional biographical photometer only displays a hemoglobin signal variation obtained from light such as transmitted through a living body and reflected therein in a form of time course graph or topography, a judgment of the above referred to diseases and the like from the displayed graphs has to rely on experiences and requires a high specialization.